The present invention relates generally to a high efficiency refrigeration system and, more specifically, to a refrigeration system utilizing one or more vortex generators and a diffuser to increase the overall efficiency of a refrigeration system.
A refrigeration system typically consists of four major components connected together via a conduit (preferably copper tubing) to form a closed loop system. Referring to FIG. 1, a conventional refrigeration system 500 is illustrated. The four major components are a compressor 52, a condenser 54, an expansion device 56 and an evaporator 58. A refrigerant circulates through the four components via the conduit 59 and will have its pressure either increased or decreased, and its temperature either increased or decreased by the four components.
The refrigerant is continuously cycled through the refrigeration system. The main steps in the refrigeration cycle are compression of the refrigerant by the compressor 52, heat rejection of the refrigerant in the condenser 54, throttling of the refrigerant in the expansion device 56, and heat absorption of the refrigerant in the evaporator 58. This process is sometimes referred to as a vapor-compression refrigeration cycle. The compressor 52 includes a motor (usually an electric motor) and provides the energy to keep the refrigerant moving within the conduits and through the major components.
The vapor-compression refrigeration cycle is the principle upon which conventional air conditioning systems, heat pumps, and refrigeration systems are able to cool and dehumidify air in a defined volume (e.g., a living space, a vehicle, a freezer, etc.) The vapor-compression cycle is made possible because the refrigerant is a condensible gas and exhibits specific properties when it is placed under varying pressures and temperatures.
During the refrigeration cycle, the refrigerant enters the compressor as saturated vapor and is compressed to a very high pressure. The temperature of the refrigerant increases during the compression step. The refrigerant leaves the compressor as superheated vapor and enters the condenser.
A typical condenser comprises a single conduit formed into a serpentine-like shape so that a plurality of rows of conduit are formed parallel to each other. Metal fins or other aids are usually attached to the outer surface of the serpentine conduit in order to increase the transfer of heat between the superheated refrigerant vapor passing through the condenser and the ambient air. Heat is rejected from the superheated vapor as it passes through the condenser and the refrigerant exits the condenser as a saturated or subcooled liquid.
The expansion device reduces the pressure of the liquid refrigerant thereby turning it into a saturated liquid-vapor mixture, which is throttled to the evaporator. In order to reduce manufacturing costs, the expansion device is typically a capillary tube in small air conditioning systems. The temperature of the refrigerant drops below the temperature of the ambient air as it passes through the expansion device. The refrigerant enters the evaporator as a low quality saturated mixture comprised of approximately 20% vapor and 80% liquid. (xe2x80x9cQualityxe2x80x9d is defined as the mass fraction of vapor in the liquid-vapor mixture.)
The evaporator physically resembles the serpentine-shaped conduit of the condenser. Ideally, the refrigerant completely evaporates by absorbing heat from the defined volume to be cooled (e.g., the interior of a refrigerator) and leaves the evaporator as saturated vapor at the suction pressure of the compressor and reenters the compressor thereby completing the cycle.
The efficiency of a refrigeration cycle is traditionally described by an energy-efficiency ratio (EER). It is defined as the ratio of the heat absorption from an evaporator to the work done by a compressor.   EER  =                    Heat        ⁢                  xe2x80x83                ⁢        absorption        ⁢                  xe2x80x83                ⁢        from        ⁢                  xe2x80x83                ⁢        evaporator            ⁢              xe2x80x83                    Work      ⁢              xe2x80x83            ⁢      done      ⁢              xe2x80x83            ⁢      by      ⁢              xe2x80x83            ⁢      compressor      
In a typical air conditioning system, the refrigeration cycle has an EER of approximately 3.0 (kw/kw). As can be seen from the EER equation, the efficiency of the refrigeration system increases by decreasing the work performed by the compressor.
Vortex tubes are well known. Typical vortex tubes are designed to operate with non-condensible gas such as air. A typical vortex tube turns compressed air into two air streams, one of relatively hot air and the other of relatively cold air. A common application for prior vortex tubes is in air supply lines and other applications which utilize gas under a high pressure.
A vortex tube does not have any moving parts. A vortex tube operates by imparting a rotational vortex motion to an incoming compressed air stream; this is done by directing compressed air into an elongated channel in a tangential direction.
The present invention increases the efficiency of a refrigeration, air conditioning or heat pump system by increasing the efficiency of the refrigeration cycle. The increase in the efficiency is achieved by utilizing a diffuser that communicates with a compressor to reduce the pressure differential across the compressor and a vortex generator to assist in the conversion of the refrigerant from vapor to liquid at specific points in the refrigeration cycle.
A vortex generator is designed to work specifically with condensible vapors such as refrigerants. In one embodiment, a vortex generator is placed between the expansion device and the evaporator in order to increase the percentage of refrigerant entering the evaporator as a liquid, and a diffuser is placed between the vortex generator and the compressor in order to increase the pressure of vapor refrigerant before the vapor enters the compressor, which will reduce the pressure differential across the compressor. As a result, the compression ratio at the compressor decreases, and the work required by the compressor is reduced, thus increasing the efficiency (EER) of the refrigeration cycle.
Since the heat absorption from the evaporator occurs through the evaporation of the liquid refrigerant, an increase in the percentage of the liquid refrigerant entering the evaporator increases the efficiency (EER) of the refrigeration cycle and reduces the size of the evaporator for the same BTU output (i.e., cooling capacity) refrigeration system.